Uhh, don't you mean Unity? Cause this is not Unreal Engine lol. unity is a very limited engine, and requires a ton of work to make a decent game on.
I guess I really don't get the whole Unreal is better than Unity deal.
Each engine has it's strong areas and weaknesses. Overall, neither is really a cut above the other.
Unreal: Does Graphics better!
Unity: Does Voxel calculations better!
For 7Days to Die, they made the better choice at the time for their project.
Choose the engine best suited for the project.
First time game developer with little coding experience and no designated coder? Then choose Unreal for their out of the box node system.
Got a project that utilizes heavy CPU calculations? Then use Unity.
Either way, both Unity and Unreal engines are still being improved upon but so far neither has the deceive edge.
I have and use both, off and on.
Nothing as grand as making a purchasable game..yet! but I still haven't seen where one is overly better than the other.
If I had my pick: I would like 7D2D2 use the VRage engine for future Voxel based projects that it was specifically made for.. or they (TFP) eventually make their own. Hopefully this game makes it a reality for them to do so.
OFC this is just my opinion based on using both/reviews etc,. and I'm not a guru, so take it for what it is as I just fail to understand this whole one engine is better than the other deal.